Centrifugal switch



IElg- 1- Dec. '25, 1928. 1,696,621

r H. L. BRUMP CENTRIQFUGAL SWITCH Filed Au 7, 1924 co-operate with the commutator segments to.

Patented Dec. 25, i928.

UNITED STATES PATENT orrifcs.

HERBERT L. BR'UMP, OF DAYTONJOHIO, ASSIGNOR TO THE DAY-FAN ELECTRIC COM- PANY, OF DAYTON, OHIO, A CORIORATION OF OHIO.

- cnurnmuear. swrrcn.

( Application filed August 7, 1924. Serial No. 730,717.

commutator motor, or for similar purposes.

One of the principal objects of the present invention is to provide a simple and reliable device in which the contact members move quickly and with certainty into and out of their contact making positions;

Another object of the invention is to provide a unitary structure which may be placed on. an armature shaft and adapted to short-circuit the same.

Other objects of the invention will be ap parent from the following description when taken in connection with the accompanying drawings, in which Fig. 1 is a longitudinal section of the centrifugally operated mechanism applied to the armature shaft of an alternating current commutator motor in position to short-circuit the commutator thereof.

Fig. 2 is a view similar to Fig.1 showing the contact members in their commutator short-circuiting position. I. Fig. 3 V 3-3 of Fig. 2, parts being broken away.

Fig. 4 is an enlarged view of a detail of the spring construction; and

Fig. 5 shows enlarged views of a contact member. Referring to the drawings, designates the armature shaft of an alternating current commutator motor, the commutator Sgf+ commutator segments 21 are mounted u pon merits of which are indicated at 21.

the armature shaft 20 in any suitable or welllrnown manner, it being understood that the commutator segments are properly insulated from one another and from certain other parts of the motor. The commutator is undercut to provide an inner cylindrical surface 22 which is adapted to be engaged by a series of, contact members 23. The inner cylindrical surface of the commutator presents, in e-fiect, a series of contacts for engagement by the contact members 23.

Secured to the armature shaft 20 is a support 24 upon which are mounted a pair of disc-like plates 25 and 26, the outer or peripheral portions of which are formed to provide an annular supporting channel 27 of substantially circular cross section for is an elevational view on the line' pivotally supporting the contact members 23. The edges of the disc members 25 and 26 are evenly spaced'so as to provide an annular slot 28 atone side of the supporting channel. Each contact or weight member 23 is formed as a plate and is provided at one end with a circular enlargement 29 which is adapted to fit loosely in the channel 27 and to form a pivot for the contact member. The other endof the contact member 23 is enlarged to form a head or hammer-like portion of such weight that when the armature shaft reaches a predetermined speed of rotation the contact members will move outwardly under centrifugal force into engagement with the contacts or commutator segments 21. Each contact member is provided with a suitable contact surface 30 for engagement with the commutator segments.

Outward movement of the contact members is resisted by a circular spring or annular resistance device 31. This annular resistance device is preferably in the form of a garter spring, the turns of which are closely wound. The ends of the spring may be joined by means of a smaller similarly wound coil spring 32 over which the two ends of the spring 31 are screwed, as indicated in Fig. 4. The contact-engaging memmeans of the circular spring 31, and in their innermost position they are stopped by the peripheral edge of the disc supporting plate 25 as shown in Fig. 1. When the armature shaft reaches a predetermined speed of rota- ;tion the contact weights or members 23 move outwardly under centrifugal force into engagement with the armature segments or contacts 21 as shown in Fig. 2.

It will be noted upon comparing Figs. 1

and .2 that each contact member 23 is provided at 33 with a bearing edge or surface for the annular spring 3l,the bearing surfaces 33 being so disposed that when the contact member 23 is in itsinnermost position the left end of the bearing surface slopes towards the armature shaft 20 and when the contact member 23 is in its outermost position the right hand end of the bearing surface 33 slopes towards the shaft 20. As a consequence of this construction the annular spring 31, which bears freely on the hear ing surface 33, moves to a pointon the bearing surface 33 as far as possible from the pivot 29 when the contact members 23 are in their inner or non-contacting-making position as shown in Fig. 1. In'this position of the spring 31 it exerts its maximum pressure or resistance to the outward movement of the contact members 23 owing to the disi will-be observed that in this latter position the pressure of the spring 31 tending to re sist the outward movement of the contact members 23 is greatly reduced owing to the 1 fact that the point of application of the pressure is close to the pivot of the contact members 23. I a

As a consequence of the shifting of the spring towards the pivot.v of the contact members 23, it will be perceived that as soon as the contact members 23 begin to move outwardly under centrifugal force the resistance of the spring 31 is decreased so that the contact members 23 move into engagement with the contacts with great certainty and: rapidity and by reason of the reduced pressure of the spring 31upon the contact members 23 in their contacting position, the

latter are enabled to exert greater contact making pressure against the contacts 21. As

' the speed of rotation of the shaft, and therefore I the centrifugal force, decreases, the spring 31 will move the contact members inwardly and thismovement is equally as positive and rapid as the outward movement of the contact members 23.,

In assembling the device the contact members 23 are preferably placed in position between the disc plates 25 and 26 aflange is turned or pressed up from the support 24 to rigidly clamp the plates to the support. f The contact members are loosely held 1n the supporting channel 27 and there is .a slight amount of looseness between the contact members themselvesin order to give suflicient freedom of operation and to avoid unnecessary friction between the several parts. By forming or punching the contact members 23 from a strip of metal of tapered thickness,

the contact members may be made tapered or wedge shaped as shown in Fig. 5 whereby a greater number of them may be introduced in the supporting channel 27 and yet maintain a suflicient looseness between the contact mem bers in their innermost position. This wedge shaped construction also has the ad.- vantage th'atit provides a relatively large contact surface 30 on each contact member.

To further insure good contact between the contacts or commutator segments 21 and the contact members 23, the latter are made after which members with each commutator segment as might occur in the case of .thick contact members. In order to prevent any possibility of the contactmembers 23 bunching together in one portion, of the supporting channel 27, and perhaps some of thecontact members falling over and piling up or binding on each other, thecon tact members are separated into groups and each groupis restricted to a definite part of the supporting channel 27. This is accomplished by providing certain of the contact members with readwardly projecting lugs or tongues 35 which are adapted to be received in radial slots or grooves 36 formed in the plate 26, the lugs-35 and slots 36 being so proportioned and fitted as to prevent any objectionable tipping of the contact members 23 in the supporting channel 27. Thecoutact members 23 onwhich thet-ougues 35 are formed may be regarded as spacing members which not only space and maintain the contact members 23 in groups but also themselves function as contact members.

From the foregoing it will be apparent that the presentinvention accomplishes its stated objects in providing a unitary device which is simple in construction and positive and rapid in operation.

While the form of apparatus herein described constitutes" a preferred embodiment of the invention, it is to be understood that the invention is not limited to. this precise form of apparatus, and that changes may be made therein without departing from the scope the appended claims. Likewise it will be understood thatthe invention is not limited .to the application thereof herein illustrated, butis susceptible of other applications.

What is claimed is:

1. In an alternating current motor having a commutator, meansfor short-circuiting said commutator, including a pivotally movable member adapted to move outwardly under centrifugal force -to engage said commutator, and yielding means exerting a pressure on said movable member tending to resist the outward movement thereof, said yielding means being mounted for varying positioning according to theoutward movement of the pivotally movable member so that the eifective pressure on the movable of the invention which is defined in I memberin its outward position does not exceed the pressure thereon in its inward position.

2. In an apparatus of the character described, a rotatable shaft, contacts arranged about said shaft, and centrifugal means carried by said shaft for engaging the contacts at a predeterminedspeed, said centrifugal means comprising outwardly movable ivotally mounted weight members, and a single yielding means connected with said weight members and exerting a pressure thereon tending to move the same inwardly, saidyielding means being mounted for bod- \5 ily movement with respect'to the axes of rotation of the pivotally movable members so that the effective pressure exerted upon the weight members in their outward position is less than thepressure thereon in,

the weight members 'in their outward positions at a value not exceeding the turning moment in their inward positions.

4. In an apparatus of the character described, a rotatable shaft, contacts arranged 40 about said shaft, and centrifugal means carried by said shaft for engaging the contacts at a predetermined speed, said centrifugal means comprisin outwardly movable pivoted weight mem ers, a circular spring connected with said weight members and ex erting a pressure thereon tending to move the same inwardly, said spring being shiftable with relation to the axis of rotation of the pivoted weight members so that the effective pressure exerted upon the weight members in their outward position does not exceed the pressure thereon in their inward position, said weight members andspring being spaced from said shaft.

' 5. In an apparatus of the character described, a rotatab e shaft, a contact spaced from the shaft, centrifugalr means carried by said shaft for engaging the contact at a predetermined speed, said centrifugal means including an elongated fiat movable member and yielding means for resisting the movement of the movable member, the connection between said yielding means and themovable member being shiftable longifie tudinally of the latter.

M faces are inclined towards the shaft therebyv fried by said shaft for engaging the contact at a" predetermined speed, said centrifugal means including a pivoted movable member -and yielding means connected with the movable member and resisting the movement of the 'movable member, said connection being adapted to shift towards or from the pivot of the movable member during movement of the latter..

In an apparatus of the character described, a rotatable shaft, contacts arranged about the shaft, and centrifugal means carried by the shaft for engaging the contacts at a predetermined speed, said centrifugal means including a' plurality of movable thin members arranged about the shaft and each disposed longitudinally with respect to the shaft, and yieldable means engaging the edges of the movable members and resisting movement thereof, said engagement 1 with themovable members being shiftable longitudinally of the movable members.

8. In an apparatus of the character described, a rotatable shaft, contacts arranged about the shaft, and centrifugal means car ried by the shaft for engaging the contacts at a predetermined speed, said centrifugal as means including a plurality of movable members arranged about the shaft and each disposed longitudinally with respect to the shaft, each movable member being rockablc and provided with a bearing surface, an annular resistance device engaging said bearing surfaces and resisting movement of the movable members, said bearing surfaces be ing so disposed that when the members'are rockedto their extreme positions in either my, direction opposite ends ofthe surfacesare. inclined towards the shaft thereby causing shifting of the annular resistance device on the bearing -surfaces'of the movable members.

9. In an apparatus of the character de scribed, a rotatable shaft, contacts arranged about said shaft, a plurality of contact members arranged in'an annular series about the shaft and outwardly movable under the action of centrifugal force to engage said contacts, a support for the contact members comprising .an annular supporting channel,

llH

- spacing means between said contact members wlthln said channel to maintain the contact members in operative position in relation to the support, said spacing means belng operable as a contact member, and spring means tending to'hold said contact members out of engagement with said contacts, said contact members being provided with hearing surfaces so disposed that when the members are rocked to their extreme positions in either direction opposite ends of the surcausing shifting of the spring means on the bearing surfaces of the contact members.

10. In an apparatus of the character described, a rotatable shaft, contacts arranged about said shaft, and pivoted contact'members arranged in an annular series about the shaft and adapted to move into engagement with said contacts, a support carried by the shaft comprising a pair of adjacent discs having complementary bulged periph eral portions providing an annular channel adapted to receive and pivotally support the contact members, spacing means in said channel adapted to space said contact mem.'

bers into groups and maintain the same in operative position in the channel, said spacing means consisting of a plate having tongue and groove connection with said support, and means tending to hold said contactmembers out of engagement with said contacts.

11. In air apparatus of the character de: scribed, a rotatable shaft, contacts arranged about said shaft, and pivoted contact members arranged In an annular series about the shaft and adapted to move into engagement with said contacts, a.support carried by the shaft and having a pair of plates with peripheral rovide an annular supporting channel 0 substantially circular cross-section adapted to receive and pivotally support the contact members, movable spacing means in said channel adapted to'space said contact members into groups and maintain the same in operative position in the channel, and said spacing means being pivoted and operable as a contact member, and means tending to hold said contact members out of engagement with said contacts.

12. In a short circuiter for motors, a series of oscillatory arms arranged in annular series in proximity to the lateral face of the motor commutator and subject to oscillation by centrifugal influence radially in relation with the axis'of rotation of the commutator,

' a fulcrum mounting for the arms located in cillatory arms, and capable of shifting movement thereon, relative to their fulcrurns to vary the yielding resistance of the spring member as said arms swing outward against the tension of said spring member under centrifugal influence to effect the electrical interconnection of said bars one with another.

I -13. In a short circuiting device for commutators, an annular series of oscillatory contact members located in juxtaposition to the commutator bars and 'engageable therewith upon outward oscillatory movement under centrifugal influence, a fulcrum mounting for said contact members,

and a spring resistance member having de-- creasing retarding action upon said contact members as they move outwardly and against the yielding resistance of which the contact members are movable into short cireuiting engagement with the commutator bars.

14. In a short circuiting device for commutators, an annular series of oscillatory contact members located in' justaposition to the commutator bars and engageable'therewith upon outward oscillatory movement under centrifugal influence, a fulcrum mounting for said contact members, and a spring resistance member operatively en gaging the contact members at different distances from their fulcrum points as the contact members are moved outwardly under centrifugal influence thereby varying the yielding resistance against which the contact members are movable into short circuiting contact with the commutator bars.

signature.

HERBERT L. BRUMP. 

